PEORIA, Ariz. -- Jon Lester's defensive skills have been well-documented. Last year, he ended a streak of 66 straight games in which he did not throw to first by doing so, but he overthrew Anthony Rizzo for an error on the play. How often does the Cubs pitcher work on his defense?

The Mariners kept Lester busy in the left-hander's first spring start. Luis Sardinas was safe on a bunt single in the first, and Robinson Cano followed with a comebacker that Lester fielded and threw underhand to Taylor Davis at first for the out.

With a runner at second in the Mariners' second inning, Steve Clevenger hit a ball that Lester threw to second, but the pitcher was charged with an error as Arismendy Alcantara couldn't handle the throw. Three batters later, Stefen Romero reached on an infield single that Lester said "handcuffed" him.

Romero's RBI Single

CHC@SEA: Romero drives in his second RBI

3/10/16: Stefen Romero's line drive single deflects off Jon Lester, scoring Luis Sardinas to extend the Mariners' lead to 6-3

"You go back to the Minor Leagues, high school, or whatever, it's something I've never been comfortable with," Lester said. "I'm a bigger guy, and I have a harder time with being in the infield. ... It's something I've just not felt comfortable with.

"Back to my Boston days and here, every day I do something, whether it be picks, whether it be fielding ground balls and throwing to first, throwing to second, throwing to third, throwing to home, whatever it may be. There's certain days we do the full gamut, there's days we do five to 10 to 15 [throws]. I put in the work. Every day. I'm prepared.

"I go out there and I give you everything I have, whether it's trying to field a ground ball or a pickoff throw to first, whatever it is, I give it everything I've got. I'm prepared for the moment. It's a matter of executing the play."

Lester on two-inning outing

CHC@SEA: Lester discusses Cactus League outing

3/10/16: Jon Lester discusses his performance after surrendering six runs in his two-inning Cactus League outing

He wasn't the only one charged with an error in the Cubs' loss to the Mariners on Thursday, but three miscues in the second led to three unearned runs. Lester served up seven hits over two innings, striking out three.

Other teams know Lester's comfort level as a fielder, and they will likely try to take advantage of it. That's why he's doing the daily drills.

"It's a matter of controlling what [opponents] are trying to do," Lester said. "That got better at the end of the year for me [last season]. It will get better this year. We're working on some other things to get some throws over there. It's all on me to make his job a lot easier. The guys don't steal on catchers, they steal on pitchers."

Speaking of catchers, this will be Lester's last year with David Ross, who has announced he's retiring at the end of the season. Lester said Ross "picked me up more last year than any other year." He'll have to transition to a new catcher next year.

"Regardless of who's back there, it's my job to be better," Lester said. "I've always believed that guys like Billy Hamilton, you might as well throw the pitch and let him go. Just get it over with and say, 'Hey, man, just go and do your thing.'

"I know I have to be better at it, and I know I have to make better throws to the catcher so they have a better chance ... to be competitive with throws."